[VoodooChile]

We did the lawn for a client in one of the area's tony gated communities last season, and noticed lots of areas for improvement, including a New Hollandstone patio that is failing.

Approximately 120 s.f. is on a rectangular concrete pad and fine. The remaining 270 s.f. is on 1" road gravel, 8" traffic bond, and 1-2" coarse sand and settling badly. No fabric appears to have been set under the base.

I imagine to repair the patio we will need: 1) to label the soldier course and cut perimeter pavers, 2) to remove and set aside (nearby!) the failed part's pavers, 3) to remove and dispose of the sand, 4) to replace the sand with lime fines, screed, and compact, and 5) relay the pavers.

My concern is that the water shed from the part of the patio with a concrete base will flow into the part of the patio with a permeable base and continue to pull the pavers below grade.

Would polymeric sand impede the flow of water into the base material to prevent settling? Is replacing the permeable base with a concrete pad the only way to insure patio integrity? Are lime fines impermeable enough to resist settling?

This would be a good project to tackle late Winter/early Spring, get the client's cash flowing and inspire enough confidence to tackle badly needed barrier and foundation plantings, high-profile stuff that could generate plenty of work in the surrounding booming neighborhood...

Thanks in advance!

[VoodooChile]

Here's the seam between the concrete and permeable base.

[VoodooChile]

Detail shot of the transition zone.

[VoodooChile]

I suspect the drain tile contributed to the failure.

[VoodooChile]

Heading out into the yard. Looks crappier in real life, and is absolutely an accident waiting to happen.

[prapoza]

This may be a stupid question but wht not put the whole thing on a concrete pad?

[Paul]

The failure at the base change is usual for contractors that don't deal with this type of base, it also might not be their fault. Most concrete sub base isn't installed as carefully as a paver base is and failure to match base compaction leads to the first fault. The base under the concrete being softer allows the paver base to migrate under the concrete.

The edge failure is typical of a base not extending beyond the finish edge far enough. The "book" recommends 6" but for heavy traffic flows I have gone farther.

The downspout drain should be a hard pvc, I like to use SDR 35 but we have gone as high as SDR 17 for heavy load or high traffic areas. That light weight pipe will collapse under normal compaction and if not compacted enough you get base failure. Also for your climate you should have some type of winter freeze prevention. I like to see a 2" air gap between the pipe and the down spout.

[guido]

If you think the cause is the base washing out from the watersehed off the concrete pad, you might want to think about running some type of drain under the pavers on the concrete pad toward the end....so the water will drain away fromt he pad instead of down to the next pad.

Also, just fixing the sand / screedings will not solve your base problem......looks like it needs to be dug and some fabric thrown down......or there will be a repeat of base failure.

[VoodooChile]

Paul's point about lack of base compaction under the concrete is a good one and escaped me completely. At a bare minimum we would need to trench along the transition line a couple of feet wide and lay some fabric to prevent further settling under the concrete.

Guido's right, that it probably would be best to excavate the whole thing done to the road gravel and lay fabric, but wow that's a big lick of work, removing, storing and spreading again roughly 8 yards of base material.

It might just be easier to excavate down six inches, dispose of the base, and pour concrete...Then again, access is an issue. The patio is in back and there is no truck access; a skid-steer could make it around back though. Not being a concrete man, this option doesn't excite me much...I would have to get bids for a project the client hasn't even broached with me (maybe I'm being too proactive in my sales approach here).

This is a bigger pain in the ass than I would have guessed; another argument for doing it right the first time.

[Stonehenge]

If I had to repair this one, I would first push very hard to be able to remove all of the concrete and do the whole things over. I can't count the number of times people wanted to lay a larger paver project over a small concrete slab just to save a few bucks.

Failing that I would remove some of the pavers on the concrete and lay a taught piece of geogrid to bridge the concrete and the transition point, extending a foot or more into the non-concrete area. This would be done after you re-prepped the sunken area. Then anchor the geogrid (a tightly woven one, like the Versa-Lok fabric, would be best) to the concrete with a few tapcon screws.

And bring along some extra (new) pavers. They never go back together exactly the way the came apart, no matter how careful you are when disassembling.

And this is if I had to do this. If I didn't, I'd tell them the only way we'll tackle this is to tear it out and redo from scratch. Too much opportunity for problems otherwise.

I bid a repair/addition retaining wall project last year. Me and another reputable company came out at $8-9K for the work. Another came in at $4-5K. Even though this guy sung the praises of 'doing it right the first time', complaining about how he got screwed last time using the lowest bidder (and he really did), I thought he'd choose one of the higher bids....

Nope. Still went with the cheapest. I wanted to skiff his head and ask if he had learned nothing. Oh, well. Don't do this unless you know you can do a good job that won't result in callbacks. This sounds like a losing proposition to me.

[Bill Schwab]

Another thing you can do short of demo is to pour a bond beam to the frost line, which I believe is 42", get a 9" bucket on a mini X and do a trench pour. Form the last few inches and you can use Surbond goober goop to stick the pavers down. Then infill the center with 6" of CA-6, recrush would be fine. Assuming of course that is how they grade gravel in Wisconsin. It might be a whole bunch easier than removing all the pavers and demoing the concrete.

Like Paul says, run some SDR 35 with a gutter connector out to daylight. If that way does not work for your needs,
I would do like Jeff says, rip it out and lay it all on gravel base like it was a new patio.

[cutntrim]

It looks like that seam is where the pathway from the seating area of the patio begins. Perhaps if the walk was stepped-down off of that concrete pad originally, along with the drainage pipe suggestions mentioned above, then that seam would not have become a problem? Too much effort to step it down now?

[PSUscaper]

I'm with stone on this one. I would rip out that concrete under the stoop.....it looks to be a fairly small area in the picture, and that is the only thing I could think of doing that I would put my faith in fixing the problem.

As for the rest of the patio, it looks suspect to having a good base. Depending on budget, I would at least start by pricing it out as a complete redo......

And when I say redo, I mean complete removal, re-dig and dispose of the base, install new base, and then relay the pavers....and don't try to relay it the exact same way. Buy some new extra pavers, and relay/re-cut the whole thing using the old and some new.

If that isn't in the budget, I would just price it out by repairing the edge and fixing any bad spots.

And I laugh when I hear 'what am I going to do with 8 yards of base material. Its interesting to hear what is 'a lot of work' and what isn't to different contractors. Most guys would just rip it all out, dispose of it, and truck in new.

Are you a mason Voodoo? that sounds like mason talk, and is usually the reason jobs end up like the one you are showing us....."Dig!!!!....good grief"...........lol!

[VoodooChile]

I'm gonna bid it for a complete redo: remove pavers, demo the concrete, excavate base material, lay fabric, and re-install.

Actually Penn my forte is plants, so I've done some digging; hardscape help get things rolling in spring, keep things going during the hottest part of summer, and extend things into the late fall.

But you're right, one man's mountain is anothers molehill...

[PSUscaper]

Another quick thing I noticed.....how old is this patio?

from the look of the pavers, I'm guessing close to 5 years. I know that cheap pavers lose their finish quick, but from the aggregate sticking out of the the top of the bricks ( all those white specs) I'm thinking this thing is probably nearing its life span if it has a sub-standard base anyway, so that would make me think a base rennovation is due.